This invention relates to an electronic musical instrument and, more particularly, to an electronic musical instrument capable of realizing a performance effect resembling arpeggio by producing tones associated with one or more depressed keys one by one at a predetermined time interval.
Performance of arpeggio generally requires a considerable performance skill. It is particularly difficult for a beginner to play arpeggio with one hand while playing melody with the other hand.
It is therefore an object of the present invention to provide an electronic musical instrument enabling even a beginner to exercise a muscial technique resembling arpeggio. For this purpose, the electronic musical instrument according to the present invention automatically realizes a musical effect resembling arpeggio by producing musical tones one by one at a predetermined interval in response to depression of one or more selected keys and repeatedly changing pitches of these tones over selected octave ranges. The musical effect resembling arpeggio produced by the electronic musical instrument according to the invention will hereinafter be referred to as "chord pyramid" performance. This reference is derived from one mode of the arpeggio-like musical effect achieved by the present invention in which mode plural tones of depressed keys contituting a chord are produced one tone after another over one or more octave ranges in such a manner that tone pitches of the tones thus produced rise and fall in a pyramidal form.
It is another object of the invention to provide an electronic musical instrument of a type which generates key data representative of a key name of a depressed key, e.g. a digital code signal (i.e. key code) and produces a musical tone signal on the basis of such digital code signal with capability of automatically conducting the chord pyramid performance. More specifically, the instrument according to the invention can automatically conduct the chord pyramid performance in such a form that one or more notes selected on the keyboard are repeatedly produced over a plurality of octaves, each note rising in its octave pitch when it is produced next time (This form of chord pyramid performance will hereinafter be referred to as "up mode"). The instrument can further conduct the chord pyramid performance in such a form that selected notes repeatedly rise and fall in their pitch. (This form of chord pyramid performance will hereinafter be referred to as "turn mode"). A basic form of arpeggio can be simulated by such repetition of the rise in the tone pitch and repetition of the rise and fall in the tone pitch. If required, the rise, or the rise and fall, in the tone pitch is not repeated but conducted only once.
It is another object of the invention to provide an electronic musical instrument capable of producing a tone at a turning point from the rise portion to the fall portion only once and not twice while conducting the chord pyramid performance of the turn mode. Such avoidance of redundant playing of the same tone is effective for creating a closer simulation of arpeggio.
It is another object of the invention to provide an electronic musical instrument which, when a key to be depressed on the keyboard is continuously changed as in a legato performance while the chord pyramid performance is being conducted, can effect a new chord pyramid performance without interrupting an octave progress in the previous chord pyramid performance and thereby realize a smooth chord shifting. According to the invention, the octave progress in the previous chord pyramid performance may be interrupted in the case of legato performance and a new octave may be started depending upon a new key to be depressed. Accordingly, the performer can select either of the two ways of octave progress in the case of the legato type shift in a key to be depressed.
It is another object of the invention to provide an electronic musical instrument which is capable of not only producing tones of a plurality of depressed keys one by one from the lowest tone upwardly or vice versa at a predetermined interval without regard to the order of depression of the keys but also repeatedly producing tones of notes which the performer arbitrarily selects at an interval he desires and in the order of depression of the keys over a plurality of octaves. The performer therefore can select either of the two functions of the instrument in the chord pyramid performance. The former function in the chord pyramid performance will hereinafter be referred to as "regular mode" whereas the latter function as "random mode". If the performer selects the random mode, he can automatically play arpeggio over a plurality of octaves while maintaining the interval of tone production selected at his will.
For achieving the above described objects, the electronic musical instrument according to the invention is adapted to generate, in response to depression of a key, a key code consisting of binary data and representing the note-name, octave-name and keyboard-name of the depressed key, drive a chord pyramid counter at a high rate for counting operation in response to a timing signal determining an interval of tone generation in the chord pyramid performance, stop the counting operation of the counter temporarily every time the counting contents of the counter and contents of the key code coincide with each other, and generate a musical tone identified by the key code. Key codes for a plurality of depressed keys are supplied in a time sharing manner through a tone generation channel assigning circuit which is herein referred to as a "key assigner" or a "channel processor" for comparison with the contents of the chord pyramid counter. The chord pyramid counter which has suspended its counting operation resumes counting from the suspended counting contents upon receipt of a next timing signal appearing when a predetermined tone production interval has elapsed and continues counting until coincidence of another key code and the counting contents. Upon detection of the coincidence, the counter again stops counting and a tone identified by the key code is produced. In the foregoing manner, tones identified by one or more keys depressed on the keyboard are produced one by one at a predetermined time interval.
The chord pyramid counter is composed of, for example, an up-down counter having a modulo corresponding to the number of keys provided on a keyboard. When counting contents overflow (or become a predetermined maximum or minimum value) in the course of counting and a carry signal is produced, this signifies completion of detection for one cycle of the coincidence between the key codes with respect to all of the depressed keys and the counting contents of the counter. In response to this carry signal, an octave number is counted and stored by a chord pyramid octave counter. The performer selects a desired octave range (i.e. an octave number) in which the chord pyramid performance is to be conducted. When the selected octave number coincides with the octave number in the octave counter, the contents of the octave counter are returned to the original state in the case of the "up mode," whereas counting modes of the chord pyramid counter and the octave counter are changed in the case of the "turn mode".
In other words, the chord pyramid performance in the up mode can be conducted with the chord pyramid counter always being set in an up-counting mode but in the case of the chord pyramid performance in the turn mode, the counting modes of the chord pyramid counter and the octave counter must be changed from an up-counting mode to a down-counting mode or vice versa each time the performance through a desired number of octaves has been completed.